The effect of vacuum heat treatment on microstructure, Al diffusion and thermal cycling lifetime of yttria stabilized zirconia by EB-PVD

Abstract

Thermal barrier coatings (TBCs) with NiCrAlYSi bond coating and yttria stabilized zirconia ceramic coating were prepared by arc ion-plating PVD and electron beam-physical vapor deposition. The NiCrAlYSi BC was investigated by different vacuum heat treatment (VHT). Composition, phase and microstructure were studied by different characterization methods included scanning electron microscope and X-ray diffraction. With the temperature of VHT increasing, the growth and evolution of pores occurred on the interface between bond coating and substrate. The Al diffused from bond coating to substrate which played an important role in the high thermal performance of TBCs. The thermal cycling behavior and failure mechanism of Y2O3-stabilized ZrO2 TBCs were evaluated and discussed in detail. The controlling of the diffusion rate of Al within NiCrAlYSi layer and the relatively low growth rate of thermally grown oxide appear to be relevant with the failure mechanism and high thermal performance.